<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .fade-enter-active,
        .fade-leave-active {
             transition: opacity .5s;
             }
        .fade-enter, 
        .fade-leave-to{
            opacity: 0;
        }
    </style>
</head>
<body>
    <div id="app">
        <transition name="fade">
            <p v-if="show">hello</p>
        </transition>
        <button @click='handleClick'>按钮</button>
    </div>
    <script src="../vue.js"></script>
    <script>
        new Vue({
            el:'#app',
            data () {
                return {
                    show:true
                }
            },
            methods: {
                handleClick(){
                    this.show=!this.show;
                }
            }
        })
    </script>
</body>
</html>